Chapter 2
This presentation is the property of its rightful owner.
Sponsored Links
1 / 13

Chapter 2 PowerPoint PPT Presentation


  • 67 Views
  • Uploaded on
  • Presentation posted in: General

Chapter 2. Scientific Method. Scientific Method. Scientific method- logical approach to solving problems by observing & collecting data, formulating hypotheses, testing hypotheses, formulating theories supported by data Examples of problems… Observable data

Download Presentation

Chapter 2

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Chapter 2

Chapter 2

Scientific Method


Scientific method

Scientific Method

  • Scientific method- logical approach to solving problems by observing & collecting data, formulating hypotheses, testing hypotheses, formulating theories supported by data

  • Examples of problems…

  • Observable data

    • Qualitative = descriptive (turn pink)

    • Quantitative = numerical (1 gram)


Chapter 2 4536713

Data

  • We cannot observe everything all at once, so we focus on a system

  • System- specific portion of matter chosen for study (ex. Reaction in a test tube)

  • Once we obtain data, we can establish patterns

  • Patterns can be made into scatter plots, bar graphs, pie charts, etc.


Hypothesis

Hypothesis

  • Once we have looked for patterns, we form a hypothesis

  • Hypothesis- testable statement in the form of “if…then…”

  • Then we have to test the hypothesis

    • Control(s)- stay constant (placebo)

    • Variable(s)- change, only changed one at a time

    • If wrong, change or drop hypothesis (might start over)


Hypothesis con

Hypothesis (con.)

  • If correct, explain through models

  • Model- explains how events occur or are related in a visual, verbal, or mathematical way

  • Theory- broad generalization that explains group of facts or events

  • Publish results (letters, scholarly journals, blog, word of mouth)


Metric system

Metric System

  • SI, or SystèmeInternationaled’Unités (French)

  • Base units

    • Length (lowercase L) = meter (m)

    • Mass (m) = kg (kilogram)

    • Time (t) = second (s)

    • Temperature (T) = Kelvin (K)

    • Amount of substance (n) = mole (mol)

    • Electric current (I) = ampere (A)

    • Luminous intensity (Iv) = candela (cd)


Metric prefixes

Metric prefixes

  • Mega (M) = 10 6

  • Kilo (k) = 10 3

  • Hecto (h) = 10 2

  • Deka (da) = 10 1

  • Deci (d) = 10 -1

  • Centi (c) = 10 -2

  • Milli (m) = 10 -3

  • Micro (µ) = 10 -6

  • Practice problems on board


Mass vs weight

Mass vs. Weight

  • Mass = amount of matter

  • Weight = amount of gravity pull

  • On moon, gravity 1/6 that of Earth

  • Didn’t lose mass, lost weight


Derived si units

Derived SI units

  • Combinations of base units

  • Area (A) = lxw = m2 or cm2

  • Volume (V) = lxwxh = m3 or cm3

  • Density (D) = kg/m3 or g/cm3 or g/mL

  • Molar Mass (MM) = kg/mol

  • Energy (E) = Joule (J)


Accuracy vs precision

Accuracy vs. Precision

  • Accuracy- close to accepted value

  • Precision- close to measurements made in same way

  • Drawings on board


Percent error

Percent Error

  • Goal = 0

  • (Experimental – Accepted)/(Accepted) x 100

  • Problems on board


Significant figures

Significant figures

  • All digits but last one certain

  • Rules

    • Nonzero = significant

    • Zero in between nonzero (2002) = significant

    • Zero in front of nonzero = not significant

    • Zero at end of number and to right of decimal = significant

    • Ex. 2000 = 1 sig, 25.00 = 4 sig, .0001 = 1 sig

    • Examples on board


Rounding

Rounding

  • 1->4, round down

  • 6->9, round up

  • 3.5->4

  • 4.5->4

  • Sig + or – Sig= same # of decimals

  • Sig x or / Sig = same # of sig digits

  • Examples on board


  • Login